72,227 research outputs found
Isotropic Chiral Objects With Zero Backscattering
In this paper we study electrically small chiral objects with isotropic
response and zero backscattering. A bi-isotropic sphere is used as a simple
example and its zero-backscattering conditions are studied. A theoretical model
of an object composed of three orthogonal chiral particles made of conducting
wire is presented as an analog of the zero-backscattering bi-isotropic sphere.
A potential application of the object as a receiving antenna or a sensor with
the ability to receive power from an arbitrary direction without backscattering
is discussed.Comment: 8 pages, 1 figure, submitted to IEEE Trans. Antennas Propa
Unrecognized Backscattering in Low Energy Beta Spectroscopy
We present studies on electron backscattering from the surface of plastic
scintillator beta detectors. By using a setup of two detectors coaxial with a
strong external magnetic field - one detector serving as primary detector, the
other as veto-detector to detect backscattering - we investigate amount and
spectrum of unrecognized backscattering, i.e. events where only one detector
recorded a trigger signal. The implications are important for low energy
particle physics experiments.Comment: 5 pages, 8 figures; v2: published NIM A versio
Coherent inelastic backscattering of intense laser light by cold atoms
We present a nonperturbative treatment of coherent backscattering of intense
laser light from cold atoms, and predict a nonvanishing backscattering signal
even at very large intensities, due to the constructive (self-)interference of
inelastically scattered photons.Comment: minor change
Coherent Backscattering with Nonlinear Atomic Scatterers
We study coherent backscattering of a quasi-monochromatic laser by a dilute
gas of cold two-level atoms. We consider the perturbative regime of weak
intensities, where nonlinear effects arise from {\em inelastic} two-photon
scattering processes. Here, coherent backscattering can be formed by
interference between {\em three} different scattering amplitudes. Consequently,
if elastically scattered photons are filtered out from the photodetection
signal by means of suitable frequency-selective detection, we find the
nonlinear backscattering enhancement factor to exceed the linear barrier two.Comment: 4 pages, 3 figure
Correction of Doppler-broadened Rayleigh backscattering effects in H2O dial measurements
A general method of solutions for treating effects of Doppler-broadened Rayleigh backscattering in H2O Differential Absorption Lidar (DIAL) measurements are described and discussed. Errors in vertical DIAL measuremtns caused by this laser line broadening effect can be very large and, therfore, this effect has to be accounted for accurately. To analyze and correct effects of Doppler-broadened Rayleigh backscattering in DIAL experiments, a generalized DIAL approximation was derived starting from a lidar equation, which includes Doppler broadening. To evaluate the accuracy of H2O DIAL measurements, computer simulations were performed. It was concluded that correction of Doppler broadened Rayleigh backscattering is possible with good accuracy in most cases of tropospheric H2O DIAL measurements, but great care has to be taken when layers with steep gradients of Mie backscattering like clouds or inversion layers are present
Interference in transport through double barriers in interacting quantum wires
We investigate interference effects of the backscattering current through a
double-barrier structure in an interacting quantum wire attached to
noninteracting leads. Depending on the interaction strength and the location of
the barriers, the backscattering current exhibits different oscillation and
scaling characteristics with the applied voltage in the strong and weak
interaction cases. However, in both cases, the oscillation behaviors of the
backscattering current are mainly determined by the quantum mechanical
interference due to the existence of the double barriers.Comment: 6 pages, 3 fig
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